Yes it’s a well known phenomenon that locking your frame rate actually makes performance worse than leaving it unlimited. If I set my monitor back to 60hz and lock the frames within the simulator to 30, the smoothness of the half refresh tweak is gone. 

When I have my frames at unlimited and 144hz my game isn't smooth. When I use half refresh rate and 60hz with fps capped at 30 fps my game feels smoother.

10 minutes ago, Airline2Sim said:

Yes it’s a well known phenomenon that locking your frame rate actually makes performance worse than leaving it unlimited. If I set my monitor back to 60hz and lock the frames within the simulator to 30, the smoothness of the half refresh tweak is gone.  

Hi, Been experimenting this this and have found the following.

1), yes locking the frame rate in P3D typically doesn't actually get you the frame rate you've set. That said I experimented with increasing the value of

• [Display]
• TEXTURE_BANDWIDTH_MULT=

The P3D default is 30, FSX-SE is 160, so I went to 160 and then incremented by 100 till I saw no appreciable changes, 760 was the result and now when I set 30 fps in the P3D slider. 30 fps is what I get.

Would proably depend on an individual machine and the silicon lottery but worth a go and it's easy to experiment with.

The advantage I see of it all is the frame rate is much more stable, and doesn't jump all over the place so much as when v-sync and unlimited frames is on.

2), To get the NVidia half refresh rate working I needed to disable Aero (I run Windows7) for which I wrote a small toggle script, so the 1/2 refresh tweak does work, although 30 Hz and v-sync is better but if I didn't have a 30 Hz monitor myself I'd use the 1/2 refresh tweak.

3), Even with 30 Hz, v-sync and unlimited framerate set a lot of spare overhead is needed as if the framerate drops under 30 v-sync drops off and a sudden and distacting "frame rate jump" occurs. (this is where the frame rate slider in P3D can help).

 

For those interested a 1080p monitor that can support a custom 30Hz value is the Dell MultiSync MHL IPS monitor (U2417H - can sync down to 23 Hz) .

Cheers

 

I thought I would just add my experience of setting a locked frame rate.

I have a Freesync monitor set at 144Hz refresh rate, which uses Nvidia G-Sync by way of the latest Nvidia drivers. I have frame rate set as unlimited in Prepar3D v4.4, but lock the frame rate to 30fps using Riva Tuner Statistics server (RTSS). Provided that you set the frame rate in RTSS before you run P3D, the frame rate is indeed locked in P3D itself (although set as unlimited) and there are no penalties associated with such frame rate locking: i.e. if without frame rate locking 40-50 fps was usually achieved, the frame rate is solid at about 30fps with frame rate locking through RTSS and not say 20-25fps or less if you had frame rate locked at 30fps from within P3D itself. I also find that it may be necessary to set VSync to ON within Nvidia Control Panel, which seems to be a recommendation by AMD for the use of Freesync with their monitors, to eliminate some minor stuttering.

In this way, my own experience is one of very smooth performance indeed, with a marked reduction in stutters and also better control of what might have otherwise been a fairly widely-varying frame rate. That is not to say that anyone else will experience the same in so doing, but spreading the knowledge may help some.

2 minutes ago, LecLightning56 said:

I thought I would just add my experience of setting a locked frame rate.

I have a Freesync monitor set at 144Hz refresh rate, which uses Nvidia G-Sync by way of the latest Nvidia drivers. I have frame rate set as unlimited in Prepar3D v4.4, but lock the frame rate to 30fps using Riva Tuner Statistics server (RTSS). Provided that you set the frame rate in RTSS before you run P3D, the frame rate is indeed locked in P3D itself (although set as unlimited) and there are no penalties associated with such frame rate locking: i.e. if without frame rate locking 40-50 fps was usually achieved, the frame rate is solid at about 30fps with frame rate locking through RTSS and not say 20-25fps or less if you had frame rate locked at 30fps from within P3D itself. I also find that it may be necessary to set VSync to ON within Nvidia Control Panel, which seems to be a recommendation by AMD for the use of Freesync with their monitors, to eliminate some minor stuttering.

In this way, my own experience is one of very smooth performance indeed, with a marked reduction in stutters and also better control of what might have otherwise been a fairly widely-varying frame rate. That is not to say that anyone else will experience the same in so doing, but spreading the knowledge may help some.

Do you have gsync on?

1 minute ago, Matt Piotrowski said:

Do you have gsync on?

Matt, yes my apologies, I do indeed have G-Sync switched on.

Just now, LecLightning56 said:

Matt, yes my apologies, I do indeed have G-Sync switched on.

Thank you, I will try this.

11 minutes ago, Matt Piotrowski said:

Thank you, I will try this.

One further thing, Matt, is that you should keep Riva Tuner Statistics Server running once having set the frame rate. In order to set frame rate in RTSS, enter e.g. 30 in the appropriate box which will flash, press enter to select it and then minimize RTSS (do not close it down). RTSS runs in the background and you will find that the frame rate stays locked in P3D (although of course set as unlimited in P3D itself).

You can also limit the frame rate in NVI.

That is what I do..  In P3D the setting is on Unlimited.

If I use 1/2 refresh rate and 30fps limit in NVI do I use standard or adaptive tear control and do I use triple buffering in NVI?

5 minutes ago, Bert Pieke said:

You can also limit the frame rate in NVI.

That is what I do..  In P3D the setting is on Unlimited.

I have just had a fiddle with NVI and the frame rate limiter. In my case it does not seem to constrain the fps to that selected as effectively as Riva Tuner Statistics Server (RTSS), with NVI bringing about excursions to 37fps with a limit set of 30fps. RTSS does not do this.

First I set P3D v4.4 to Unlimited, VSync=Off, TB=Off.

Next I went into Nvidia Control Panel and Default/Applied to ensure I was starting from a fresh slate.

 

So in I go to P3D and I see high fps, I switch VSync=On and I see 60Hz which is the refresh rate of the monitor.

I switch VSync=Off, back to high fps and exit P3D.

 

Now back in NCP I set the P3D Profile to half refresh adaptive.

Back in P3D I have hundreds of fps. I switch VSync=On and I see again 60fps.

So far half refresh has not made a difference, fullscreen or windowed.

 

So I apply half refresh in the same manner to the overall profile and still no change to GPU output. I switched hdmi with displayport no change.

 

So on an ordinary display there's no difference with half refresh. Unless the desktop modes can be altered.

 

The reason is that a desktop contains the D3D viewport in a window and half refresh rate works in an exclusive mode display.

To test that, I set half refresh in NCP for the FSX profile.

 

I go into FSX and it’s starting up windowed. Checking the fps it’s in the hundreds so

half refresh does not appear to be working…

 

So now Holding down ALT and pressing Enter (the Windows command for measure my desktop area) and the sim go’s into full-screen.

I now see the fps hovering around 30fps = half of my monitor refresh frequency of 60Hz.

So here we have FSX in a full-screen, exclusive mode desktop and it is responding to half refresh for the first time tonight!

Edited March 17, 20197 yr by SteveW

If we mess around with the full-screen exclusive mode viewport we can perhaps see tearing if there is no vertical synchronisation.

The thing to note about P3D is that VSync = On in P3D Display settings is not the vertical synchronisation we associate with monitor behaviour.

P3D Vsync = On obtains the refresh rate setting of the monitor and arranges each frame to be output near that frequency. So we see typically wobbling around that frequency.. We do not see a cap it is not a limit. We see the wobble because frames take differing times to complete.

Edited March 17, 20197 yr by SteveW

I tried turning HT off and I get blurry terrain but my sim runs better. Any way to fix the blurry terrain?

Edited March 17, 20197 yr by Matt Piotrowski

Are you using an affiniti mask?